Like the quest for "truth, justice, equality, peace", Mytyl and Tyltyl are guided by Berylune [a fairy] to find "happiness".
[See NOTE at the end.]
IMDb reviewer, wes-connors, wrote...
Somewhere or anywhere, during a snowy winter, young Robin Macdougall (as Tyltyl) and little sister Tula Belle (as Mytyl) learn their neighbor's child is sick. The ailing girl thinks she might be well and happy if she could only have young Tyltyl's caged bird, but Mytyl decides the siblings won't give it up. That evening, they are awakened by a winged fairy, Lillian Cook (as Berylune), who sets them off on a quest to find the elusive "Bluebird of Happiness" and put it in their suddenly empty cage.
Companions like humanized feline Tom Corless (as Cat) consider sabotaging the mission, because he, canine Charles Ascot (as Dog), and other manifestations of inhumanity learn they will cease to exist if and when the children achieve success. Tyltyl and Mytyl search far and wide for the Bluebird of Happiness - meeting not only their dead grandparents, but also their future brother during their journey - but the creature remains hidden where they least expect to find it.
"The Blue Bird" is filled with beautiful thoughts from the original Maurice Maeterlinck play. Homilies like "Heaven is where you and I kiss each other" seems as good a definition as any. With majestic allegory by director Maurice Tourneur, production designer Ben Carr, and their crew, it was probably unwise to try to improve this orchestrated silent version of "The Blue Bird" - and filmmakers famously failed twice. Despite the ravages of time, this is the definitive version of the classic story.
Perhaps most incredible is the not original, yet startling in context ending - young Tyltyl (Macdougall) unexpectedly "speaks" directly to the audience (about the quest) while the once sickly, but now beautiful young Katherine Bianchi smiles knowingly at his side - sister Mytyl (Belle) is regulated to the background, most definitely pondering this latest turn of events.
[NOTE: The music bed is very garbled, so, for a rare film offering like this, just turn off the sound.]